Liquid or hydraulic blow molding

ABSTRACT

An apparatus and method for simultaneously forming and filling a plastic container is provided. A mold cavity defines an internal surface and is adapted to accept a preform. A pressure source includes an inlet and a piston-like device. The piston-like device is moveable in a first direction wherein liquid is drawn into the pressure source through the inlet and in a second direction wherein the liquid is urged toward the preform. A blow nozzle may be adapted to receive the liquid from the pressure source and transfer the liquid at high pressure into the preform thereby urging the preform to expand toward the internal surface of the mold cavity and creating a resultant container. The liquid remains within the container as an end product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/328,578 filed Dec. 4, 2008, now U.S. Pat. No. 8,017,064, which claimsthe benefit of U.S. Provisional Application No. 61/005,655, filed onDec. 6, 2007. The entire disclosures of the above applications areincorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to an apparatus and method for formingand filling a plastic container. More specifically, this disclosurerelates to an apparatus and method for simultaneously forming andfilling a plastic container.

BACKGROUND

As a result of environmental and other concerns, plastic containers,more specifically polyester and even more specifically polyethyleneterephthalate (PET) containers are now being used more than ever topackage numerous commodities previously supplied in glass containers.Manufacturers and fillers, as well as consumers, have recognized thatPET containers are lightweight, inexpensive, recyclable andmanufacturable in large quantities.

Blow-molded plastic containers have become commonplace in packagingnumerous commodities. PET is a crystallizable polymer, meaning that itis available in an amorphous form or a semi-crystalline form. Theability of a PET container to maintain its material integrity relates tothe percentage of the PET container in crystalline form, also known asthe “crystallinity” of the PET container.

The following equation defines the percentage of crystallinity as avolume fraction:

${\%\mspace{14mu}{Crystallinity}} = {\left( \frac{\rho - \rho_{a}}{\rho_{c} - \rho_{a}} \right) \times 100}$where ρ is the density of the PET material; ρ_(a) is the density of pureamorphous PET material (1.333 g/cc); and ρ_(c) is the density of purecrystalline material (1.455 g/cc). Once a container has been blown, acommodity may be filled into the container.

Traditionally blow molding and filling have developed as two independentprocesses, in many cases operated by different companies. In order tomake bottle filling more cost effective, some fillers have moved blowmolding in house, in many cases integrating blow molders directly intotheir filling lines. The equipment manufacturers have recognized thisadvantage and are selling “integrated” systems that are designed toinsure that the blow molder and the filler are fully synchronized.Despite the efforts in bringing the two processes closer together, blowmolding and filling continue to be two independent, distinct processes.As a result, significant costs may be incurred while performing thesetwo processes separately. Thus, there is a need for a liquid orhydraulic blow molding system suitable for forming and filling acontainer in a single operation.

SUMMARY

Accordingly, the present disclosure provides a system and method forusing the final liquid product to impart the pressure required to expanda hot preform and to take on the shape of a mold thus simultaneouslyforming and filling the container.

In one example, the system includes a mold cavity defining an internalsurface and adapted to accept a preform. The system also includes apressure source having an inlet, a filling cylinder and a piston-likedevice. The piston-like device is moveable within the filling cylinderin a first direction such that liquid is drawn into the filling cylinderthrough the inlet and in a second direction such that the liquid isurged toward the preform. A blow nozzle may be adapted to receive theliquid from the pressure source and transfer the liquid at high pressureinto the preform thereby urging the preform to expand toward theinternal surface of the mold cavity and create a resultant container.The liquid remains within the container as an end commodity.

Additional benefits and advantages of the present disclosure will becomeapparent to those skilled in the art to which the present disclosurerelates from the subsequent description and the appended claims, takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a heated preform passed into a moldstation and being subject to an optional sterilization step, wherein apressure source including a piston-like device begins to move upward,drawing liquid into the pressure source in accordance with the teachingsof the present disclosure.

FIG. 2 is a schematic depiction of the system illustrated in FIG. 1wherein the mold halves close around the preform and liquid continues toaccumulate in the pressure source.

FIG. 3 is a schematic depiction of the system illustrated in FIG. 2wherein a stretch rod extends into the preform to initiate mechanicalstretching and wherein fluid continues to accumulate in the pressuresource.

FIG. 4 is a schematic depiction of the system of FIG. 3 wherein thestretch rod stretches the preform and wherein fluid has been fullyaccumulated in the pressure source.

FIG. 5 is a schematic depiction of the system of FIG. 4 wherein thepiston-like device drives the liquid from the pressure source to thepreform thereby expanding the preform toward the walls of the moldcavity.

FIG. 6 is a schematic depiction of the system of FIG. 5 wherein thepiston-like device has been fully actuated thereby completelytransferring an appropriate volume of liquid to the newly formedcontainer and wherein the stretch rod is withdrawing; and

FIG. 7 is a schematic depiction of the system of FIG. 6 wherein the moldhalves separate and the piston-like device begins to draw liquid intothe pressure source in preparation for the next cycle.

DETAILED DESCRIPTION

The following description is merely exemplary in nature, and is in noway intended to limit the disclosure or its application or uses.

With reference to all Figures, a mold station according to the presentteachings is shown and generally referred to as reference numeral 10.FIGS. 1-7 show one exemplary sequence according to the presentteachings. As will become appreciated from the following description,the mold station 10 and associated method utilize a final liquidcommodity L to impart the pressure required to expand a hot preform 12to take on the shape of a mold thus simultaneously forming and filling aresultant container C (FIG. 7).

With initial reference to FIGS. 1 and 2, the mold station 10 will bedescribed in greater detail. The mold station 10 generally includes amold cavity 16, a pressure source 20, a blow nozzle 22 and a stretch rod26. The exemplary mold cavity 16 illustrated includes mold halves 30, 32that cooperate to define an interior surface 34 corresponding to adesired outer profile of a blown container. The mold cavity 16 may bemoveable from an open position (FIG. 1) to a closed position (FIG. 2)such that a support ring 38 of the preform 12 is captured at an upperend of the mold cavity 16. The preform 12 may be formed of a polyestermaterial, such as polyethylene terephthalate (PET), having a shape wellknown to those skilled in the art similar to a test-tube with agenerally cylindrical cross section and a length typically approximatelyfifty percent (50%) that of the resultant container C height. Thesupport ring 38 may be used to carry or orient the preform 12 throughand at various stages of manufacture. For example, the preform 12 may becarried by the support ring 38, the support ring 38 may be used to aidin positioning the preform 12 in the mold cavity 16, or an end consumermay use the support ring 38 to carry the plastic container C oncemanufactured.

In one example, the pressure source 20 can be in the form of, but notlimited to, a filling cylinder, manifold or chamber 42 that generallyincludes a mechanical piston-like device 40 including, but not limitedto, a piston, a pump (such as a hydraulic pump) or any other suchsimilarly suitable device, moveable within the filling cylinder,manifold or chamber 42. The pressure source 20 has an inlet 46 foraccepting the liquid commodity L and an outlet 48 for delivering theliquid commodity L to the blow nozzle 22. It is appreciated that theinlet 46 and the outlet 48 may have valves incorporated thereat. Thepiston-like device 40 may be moveable in a first direction (upward asviewed in the FIGS.) to draw the liquid commodity L from the inlet 46into the filling cylinder, manifold or chamber 42, and in a seconddirection (downward as viewed in the FIGS.) to deliver the liquidcommodity L from the filling cylinder, manifold or chamber 42 to theblow nozzle 22. The piston-like device 40 can be moveable by anysuitable method such as pneumatically, mechanically or hydraulically forexample. The inlet 46 of the pressure source 20 may be connected, suchas by tubing or piping to a reservoir or container (not shown) whichcontains the final liquid commodity L. It is appreciated that thepressure source 20 may be configured differently.

The blow nozzle 22 generally defines an inlet 50 for accepting theliquid commodity L from the outlet 48 of the pressure source 20 and anoutlet 56 (FIG. 1) for delivering the liquid commodity L into thepreform 12. It is appreciated that the outlet 56 may define a shapecomplementary to the preform 12 near the support ring 38 such that theblow nozzle 22 may easily mate with the preform 12 during theforming/filling process. In one example, the blow nozzle 22 may definean opening 58 for slidably accepting the stretch rod 26 used to initiatemechanical stretching of the preform 12.

In one example, the liquid commodity L may be introduced into theplastic container C during a thermal process, typically a hot-fillprocess. For hot-fill bottling applications, bottlers generally fill theplastic container C with a liquid or product at an elevated temperaturebetween approximately 185° F. to 205° F. (approximately 85° C. to 96°C.) and seal the plastic container C with a closure (not illustrated)before cooling. In one configuration, the liquid may be continuouslycirculated within the filling cylinder, manifold or chamber 42 throughthe inlet 46 whereby the liquid can be heated to a preset temperature(i.e., at a heat source (not illustrated) upstream of the inlet 46). Inaddition, the plastic container C may be suitable for otherhigh-temperature pasteurization or retort filling processes, or otherthermal processes as well. In another example, the liquid commodity Lmay be introduced into the plastic container C under ambient or coldtemperatures. Accordingly, by way of example, the plastic container Cmay be filled at ambient or cold temperatures such as betweenapproximately 32° F. to 90° F. (approximately 0° C. to 32° C.), and morepreferably at approximately 40° F. (approximately 4.4° C.). In exampleswhere the liquid commodity is filled at ambient or cold temperatures,the preform may be subjected to a sterilization process beforeintroducing the liquid commodity as will be described herein.

With reference now to all Figures, an exemplary method of simultaneouslyforming and filling the plastic container C will be described. Accordingto one example (FIG. 1), steam S may be directed onto and/or into thepreform 12 to partially or completely sterilize the preform 12. Bysubjecting the preform 12 to a sterilizing technique (such as steam S),an aseptic preform and resulting container can be created withoutrequiring the end liquid to be the sterilizing medium. Therefore, thecontainer need not be formed by a hot-filling process. It is appreciatedthat while steam S is shown in FIG. 1, other sterilizing mediums and/ortechniques may be employed. In one example, the sterilizing medium maybe a liquid such as, but not limited to, liquid peroxide.

The preform 12 may be placed into the mold cavity 16 (FIG. 2). In oneexample, a machine (not illustrated) places the preform 12 heated to atemperature between approximately 190° F. to 250° F. (approximately 88°C. to 121° C.) into the mold cavity 16. As the preform 12 is locatedinto the mold cavity 16, the piston-like device 40 of the pressuresource 20 may begin to draw the liquid commodity L into the fillingcylinder, manifold or chamber 42 through the inlet 46. The mold halves30, 32 of the mold cavity 16 may then close thereby capturing thepreform 12 (FIG. 2). The blow nozzle 22 may form a seal at a finish ofthe preform 12. The mold cavity 16 may be heated to a temperaturebetween approximately 250° F. to 350° F. (approximately 93° C. to 177°C.) in order to impart increased crystallinity levels within theresultant container C. In another example, the mold cavity 16 may beprovided at ambient or cold temperatures between approximately 32° F. to90° F. (approximately 0° C. to 32° C.). The liquid commodity L maycontinue to be drawn into the filling cylinder, manifold or chamber 42by the piston-like device 40.

Turning now to FIG. 3, the stretch rod 26 may extend into the preform 12to initiate mechanical stretching. At this point, the liquid commodity Lmay continue to be drawn into the filling cylinder, manifold or chamber42. With reference to FIG. 4, the stretch rod 26 continues to stretchthe preform 12 thereby thinning the sidewalls of the preform 12. Thevolume of the liquid commodity L in the filling cylinder, manifold orchamber 42 may increase until an appropriate volume suitable to form andfill the resultant container C is reached. At this point, a valvedisposed at the inlet 46 of the pressure source 20 may be closed.

With specific reference to FIG. 5, the piston-like device 40 may thenbegin to drive downward (drive phase) to initiate the rapid transfer ofthe liquid commodity L from the filling cylinder, manifold or chamber 42to the preform 12. Again, the piston-like device 40 may be actuated byany suitable means such as pneumatic, mechanical and/or hydraulicpressure. In one example, the hydraulic pressure within the preform 12may reach between approximately 100 PSI to 600 PSI. The liquid commodityL causes the preform 12 to expand toward the interior surface 34 of themold cavity 16. Residual air may be vented through a passage 70 definedin the stretch rod 26 (FIG. 5). As shown in FIG. 6, the piston-likedevice 40 has completed its drive phase thereby completely transferringthe appropriate volume of the liquid commodity L to the newly formedplastic container C. Next, the stretch rod 26 may be withdrawn from themold cavity 16 while continuing to vent residual air. The stretch rod 26may be designed to displace a predetermined volume of the liquidcommodity L when it is withdrawn from the mold cavity 16 therebyallowing for the desired fill level of the liquid commodity L within theresultant plastic container C. Generally, the desired fill level willcorrespond at or near the level of the support ring 38 of the plasticcontainer C.

Alternatively, the liquid commodity L can be provided at a constantpressure or at different pressures during the molding cycle. Forexample, during axial stretching of the preform 12, the liquid commodityL may be provided at a pressure which is less than the pressure appliedwhen the preform 12 is blown into substantial conformity with theinterior surface 34 of the mold cavity 16 defining the finalconfiguration of the plastic container C. This lower pressure P₁ may beambient or greater than ambient but less than a subsequent high pressureP₂. The preform 12 is axially stretched in the mold cavity 16 to alength approximating the final length of the resultant plastic containerC. During or just after stretching the preform 12, the preform 12 isgenerally expanded radially outward under the low pressure P₁. This lowpressure P₁ is preferably in the range of between approximately 100 PSIto 150 PSI. Subsequently, the preform 12 is further expanded under thehigh pressure P₂ such that the preform 12 contacts the interior surface34 of the mold halves 30, 32 thereby forming the resultant plasticcontainer C. Preferably, the high pressure P₂ is in the range ofapproximately 500 PSI to 600 PSI. As a result of the above method, thebase and contact ring of the resultant plastic container C is fullycircumferentially formed.

Optionally, more than one piston-like device may be employed during theformation of the resultant plastic container C. For example, a primarypiston-like device may be used to generate the low pressure P₁ toinitially expand the preform 12 while a secondary piston-like device maybe used to generate the subsequent high pressure P₂ to further expandthe preform 12 such that the preform 12 contacts the interior surface 34of the mold halves 30, 32 thereby forming the resultant plasticcontainer C.

With reference to FIG. 7, the fill cycle is shown completed. The moldhalves 30, 32 may separate and the blow nozzle 22 may be withdrawn. Theresultant filled plastic container C is now ready for post-forming stepssuch as capping, labeling and packing. At this point, the piston-likedevice 40 may begin the next cycle by drawing the liquid commodity Lthrough the inlet 46 of the pressure source 20 in preparation for thenext fill/form cycle. While not specifically shown, it is appreciatedthat the mold station 10 may include a controller for communicatingsignals to the various components. In this way, components such as, butnot limited to, the mold cavity 16, the blow nozzle 22, the stretch rod26, the piston-like device 40 and various valves may operate accordingto a signal communicated by the controller. It is also contemplated thatthe controller may be utilized to adjust various parameters associatedwith these components according to a given application.

Some additional advantages realized by the present teachings will now bediscussed further.

According to one advantage, some of the processing parameters can belowered while still reaching desired results. For example, therequirements for preform conditioning can be reduced because thecrystallinity requirements can be lowered. In addition, moldconditioning requirements can be reduced which can reduce the amount ofoils and/or other surface preparation materials used on the interiorsurface 34 of the mold cavity 16.

According to one example, the integrated blowing and filling processdescribed herein can be used to form containers having carbonatedbeverages (i.e., soda, etc.). In such an example, liquid carbon dioxidecan be used in solution as part of, or in addition to, the liquidcommodity during the simultaneous blowing and filling process. Liquidcarbon dioxide prevents foaming that could otherwise occur when blowingwith a liquid commodity having gaseous carbon dioxide. Carbon dioxidemay exist in liquid form at a given pressure and temperature.

The combination of both the blow and filling processes into one piece ofequipment (mold station 10) may reduce handling parts and therefore leadto reduced capital cost per resultant plastic container C. In addition,the space required by a process that simultaneously blows and fills theresultant plastic container C may be significantly reduced over thespace required when the processes are separate. This may also result inlower infrastructure cost.

Integrating the two processes into a single step may reduce labor andadditional costs (both capital and expense) associated with handlingbottles after they are produced and before they are filled.

Integrating the blowing and filling processes into a single processeliminates the need to ship bottles. The shipping of bottles isinherently inefficient and expensive. Shipping preforms, on the otherhand, is much more efficient. In one example, a trailer load of empty500 ml water bottles contains approximately 100,000 individual bottles.The same size trailer loaded with preforms required to make 500 ml waterbottles will carry approximately 1,000,000 individual preforms, a 10:1improvement.

Compressed air is a notoriously inefficient means of transferringenergy. Using the final product to provide hydraulic pressure to blowthe container will require the equivalent of a positive displacementpump. As a result, it is a much more efficient way to transfer energy.

In the exemplary method described herein, the preforms may be passedthrough an oven in excess of 212° F. (100° C.) and immediately filledand capped. In this way, the opportunity for an empty container to beexposed to the environment where it might become contaminated is greatlyreduced. As a result, the cost and complexity of aseptic filling may begreatly reduced.

In some instances where products are hot filled, the package must bedesigned to accommodate the elevated temperature that it is exposed toduring filling and the resultant internal vacuum it is exposed to as aresult of the product cooling. A design that accommodates suchconditions may require added container weight. Liquid/hydraulic blowmolding offers the potential of eliminating the hot fill process and asa result, lowering the package weight.

The process described herein may eliminate intermediary work in processand therefore may avoid the cost associated with warehousing and/orcontainer silos and/or forklifts and/or product damage, etc. Inaddition, without work in process inventory, the overall working capitalmay be reduced.

As blowing and filling are integrated closer but remain as two separateprocesses (such as conventional methods of forming and subsequentlyfilling), the overall efficiency of such a system is the product of theindividual efficiencies of the two parts. The individual efficienciesmay be driven largely by the number of transitions as parts move throughthe machines. Integrating the two processes into one may provide theopportunity to minimize the number of transitions and therefore increasethe overall process efficiency.

Many beverages, including juices, teas, beer, etc., are sensitive tooxygen and need to be protected when packaged. Many plastics do not havesufficient barrier characteristics to protect the contents from oxygenduring the life of the packaged product. There are a number oftechniques used to impart additional barrier properties to the containerto slow down oxygen transmission and therefore protect the packagedcontents. One of the most common techniques is to use an oxygenscavenger in the container wall. Such a scavenger may be molded directlyinto the preform. The relatively thick wall of the preform protects thescavenger from being consumed prior to blowing it into a container.However, once the container has been blown, the surface area of the wallincreases and the thickness decreases. As such, the path that the oxygenhas to travel to contact and react with the active scavenging materialis much shorter. Significant consumption of oxygen scavengers may beginas soon as the container is blown. If the container is formed and filledat the same time, then the scavenger is protecting the product throughits entire useful life and not being consumed while the container sitsempty waiting to be filled.

The method described herein may be particularly useful for fillingapplications such as isotonic, juice, tea and other commodities that aresusceptible to biological contamination. In particular, by optionallysterilizing the preform as described above, an aseptic preform andresulting container can be created without requiring the end liquid tobe the sterilizing medium. These commodities are typically filled in acontrolled, sterile environment. Commercially, two ways are typicallyused to achieve the required sterile environment. In Europe, one primarymethod for filling these types of beverages is in an aseptic fillingenvironment. The filling operation is performed in a clean room. All ofthe components of the product including the packaging must be sterilizedprior to filling. Once filled, the product may be sealed until it isconsumed preventing any potential for the introduction of bacteria. Theprocess is expensive to install and operate. As well as, there is alwaysthe risk of a bacterial contaminant breaking through the operationaldefenses and contaminating the product.

In North America, one predominant method for filling contaminantsusceptible beverages is through hot filling. In this process, thebeverage is introduced to the container at a temperature that will killany bacteria that is present. The container may be sealed while theproduct is hot. One drawback to this technology is that the containersusually need to be heavy to sustain the elevated filling temperature andthe vacuum that eventually develops in the container as the productcools. As well as, the blow process is somewhat more complex andtherefore more costly than non-heat set blow molding. The disclosuredescribed herein offers the opportunity to dramatically reduce the costand complexity of filling sensitive foods and beverages. By combiningthe blowing and filling processes, there is an ability to heat thepreform to over 212° F. (100° C.) for a sufficient period of timenecessary to kill any biological contaminants. If a sterile product isused as the container-forming medium and then immediately sealed, theprocess may result in a very inexpensive aseptic filling process withvery little opportunity for contamination.

The concurrent blowing and filling process described herein can alsofacilitate the formation of a super-lightweight container. As notedabove, in traditional hot-fill containers, the container usually neededto have a suitable wall thickness to accommodate vacuum pressures. Bysterilizing the preform 12 (i.e. such as by subjecting it to steam S,FIG. 1) prior to introducing the liquid commodity, the resultant wallthickness can be much thinner relative to a traditional hot-filledcontainer. In a super-lightweight container, the liquid itself can givestructural support to the container. The walls of a super-lightweightcontainer can therefore be extremely flexible.

There are many other bottled products where this technology may beapplicable. Consumable products such as dairy products, liquor, saladdressings, sauces, spreads, ketchups, syrups, edible oils, and othersmay be bottled utilizing such methods. Furthermore, the term liquidcommodity L used herein can also include non-consumable goods such ashousehold cleaners, detergents, personal care items such as toothpaste,etc. Many of these products are currently found in blow molded PETcontainers but are also in extrusion molded plastic containers, glassbottles and/or cans. This technology has the potential of dramaticallychanging the economics of package manufacture and filling.

While much of the description has focused on the production of PETcontainers, it is contemplated that other polyolefin materials (e.g.,polyethylene, polypropylene, polyester, etc.) as well as a number ofother plastics may be processed using the teachings discussed herein.

While the above description constitutes the present disclosure, it willbe appreciated that the disclosure is susceptible to modification,variation and change without departing from the proper scope and fairmeaning of the accompanying claims.

What is claimed is:
 1. A system for simultaneously forming and filling a container comprising: a mold cavity defining an internal surface and adapted to accept a preform; a sterilizing apparatus that sterilizes the preform; a pressure source having an inlet, a chamber and a piston means moveable within the chamber in a first direction wherein liquid is drawn into the chamber through the inlet and in a second direction wherein the liquid is urged toward the preform; and a blow nozzle adapted to receive the liquid from the pressure source and transfer the liquid at a pressure into the preform thereby urging the preform to expand toward the internal surface of the mold cavity and create a resultant container, wherein the liquid remains within the container as an end product; and wherein the preform is initially expanded outwardly under a first pressure and subsequently expanded outwardly under a second pressure; and wherein the piston means comprises a first piston means that generates the first pressure and a second piston means that generates the second pressure.
 2. The system for simultaneously forming and filling a container according to claim 1 wherein the piston means is one of a piston, and a pump and an accumulator.
 3. The system for simultaneously forming and filling a container according to claim 1 wherein the blow nozzle defines a shape adapted to form a seal with a finish of the preform.
 4. The system for simultaneously forming and filling a container according to claim 1 wherein the liquid is transferred into the preform during a hot-fill process.
 5. The system for simultaneously forming and filling a container according to claim 4 wherein the liquid is transferred into the preform at a temperature between approximately 185° F. (85° C.) and approximately 205° F. (96° C.).
 6. The system for simultaneously forming and filling a container according to claim 1 wherein the liquid is transferred into the preform at an ambient temperature.
 7. The system for simultaneously forming and filling a container according to claim 6 wherein the liquid is transferred into the preform at a temperature between approximately 32° F. (0° C.) and approximately 90° F. (32° C.).
 8. The system for simultaneously forming and filling a container according to claim 7 wherein the sterilizing apparatus emits steam onto and/or into the preform.
 9. The system for simultaneously forming and filling a container according to claim 7 wherein the sterilizing apparatus emits a sterilizing liquid onto and/or into the preform.
 10. The system for simultaneously forming and filling a Container according to claim 9 wherein the sterilizing liquid comprises peroxide.
 11. The system for simultaneously forming and filling a container according to claim 1 wherein the mold cavity accepts a preform heated to a temperature between approximately 190° F. (88° C.) and approximately 250° F. (121° C.).
 12. The system for simultaneously forming and filling a container according to claim 1 wherein the mold cavity is heated to a temperature between approximately 250° F. (93° C.) and approximately 350° F. (177° C.).
 13. The system for simultaneously forming and filling a container according to claim 1 wherein the liquid is transferred into the preform at a pressure between approximately 100 PSI and approximately 600 PSI.
 14. The system for simultaneously forming and filling a container according to claim 1, further comprising a stretch rod adapted to extend into the preform and mechanically stretch the preform prior to the liquid being urged into the preform.
 15. The system for simultaneously forming and filling a container according to claim 14 wherein the stretch rod is vented to atmosphere.
 16. The system for simultaneously forming and filling a container according to claim 1 wherein the first pressure is between approximately 100 PSI and approximately 150 PSI, and the second pressure is between approximately 500 PSI and approximately 600 PSI. 